Abstract

The connection between East Australian Current (EAC) transport variability and Australia’s east coast
sea level has received little treatment in the literature. This is due in part to the complex interacting
physical processes operating in the coastal zone combined with the sparsity of observations available to
improve our understanding of these possible connections. This study demonstrates a statistically
significant (at the 490% level) relationship between interannual to decadal time scale variations in
observed estimates of the EAC transport changes and east coast sea level measured at the high-quality,
long record Fort Denison tide-gauge in Sydney Harbour, Australia (3315101800S, 15111303200E). We
further demonstrate, using a linear reduced-gravity ocean model, that ENSO to decadal time-scale
variations and the ocean-adjusted multi-decadal trend (approx. 1 cm/decade) in observed sea level at
Fort Denison are strongly connected to modulations of EAC transports by incoming westward
propagating oceanic Rossby waves. We show that EAC transport and Fort Denison sea level vary in a
manner expected from both Tasman Sea generated Rossby waves, which account for the interannual
and multi-annual variability, and remotely forced (from east of New Zealand) Rossby wave connections
through the mid-latitudes, accounting for the ocean-adjusted multi-decadal trend observed at the New
South Wales coast – with the regional-Tasman Sea forcing explaining the greatest overall proportion of
EAC transport and sea-level variances.